Energy expenditure of walruses in relation to marine productivity in the Young Sund area (eastern Greenland)

The aim of this study is to measure the energy expenditure and requirements of individual free-ranging walruses in eastern Greenland, the quantitative importance of predation on the infauna by walruses in Young Sund, and the relationship between primary production, benthic animals and walruses.

In order to describe the "predator-benthic prey" i.e. "walrus-mollusks" system in eastern Greenland a major step is to provide information about the relationship between climatic factors, ice cover, and productivity of Arctic benthic ecosystems, and factors determining the recovery of the small population of walruses in eastern Greenland.

The extent and duration of the period of dense shore-fast ice is influenced by natural short-term climatic variability and/or by large-scale climatic changes. In its turn the duration of the period where fast ice is absent (i.e. the open water period when sunlight can penetrate into the water column) is likely to be an important factor determining the magnitude of the inshore marine productivity. Because walruses are the major predators of the benthic ecosystem, they are highly sensitive to changes in the latter. One of few important East Greenland walrus feeding habitats is found in the Young Sund area where studies to determine the influence of climatic factors on marine productivity have been conducted since 1993.

Walrus movements The picture shows movements of each individual animal in different colours (SDR-Number)

The determination of area use, activity and energy-expenditure of free-ranging walruses by use of satellite telemetry and stable isotope techniques will be linked to studies aiming at determination of distribution, density, annual growth and energy contents of benthic mollusks and predation on them by walruses.

The study is a co-operation between a Greenlandic (Greenland Institute of Natural Resources http://www.natur.gl) and three Danish research institutes (National Environmental Research Institute departments for Arctic Environment and for Marine Ecology and The Royal Veterinary and Agricultural University.

The studies proposed here are connected to the ongoing Changes in Arctic Marine Production project ( financially supported by Danish Research Councils - SNF http://www.forsk.dk/snf - grant # 9700224). The aim of the CAMP project is to investigate the responses of production, consumption, and degradation in Arctic coastal ecosystems to changes in temperature and sea ice-cover due to global warming. The main objective is to study the mechanisms controlling primary production and the subsequent regula-tion of secondary production and bacterial recycling of nutrients.

Furthermore, association with the ongoing CAMP project will provide data forming a link between global temperature changes and biological production and consumption in Arctic marine ecosystems covering unicellular algae and bacteria through large mammals. Hence, the studies of benthic animals and walruses in this project, is a unique opportunity to integrate results obtained from two different perspectives. Information obtained from studies of marine ecological processes can support information obtained from studies of energetic processes in a key player of the system (the walrus) - and vice versa.

Walrus with satellite tag

	Changes in Arctic Marine Production project http://www.dmu.dk/LakeandEstuarineEcology/CAMP/index.htm
	The aim of the CAMP project is to investigate the responses of production, consumption, and degradation in Arctic coastal ecosystems to changes in temperature and sea ice-cover due to global warming.